/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2009 Duy Nguyen 

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Duy Nguyen <duy@soe.ucsc.edu>

 * 

 * Some Comments: 

 * 

 * 1) Segment Size is declared for completeness but not used  because it has 

 *    to do more with the requirement of the specific hardware.

 *

 * 2) By default, Minstrel applies the multi-rate retry(the core of Minstrel 

 *    algorithm). Otherwise, please use ConstantRateWifiManager instead.

 *

 * http://linuxwireless.org/en/developers/Documentation/mac80211/RateControl/minstrel

 */

#include "minstrel-wifi-manager.h"

#include "wifi-phy.h"

#include "ns3/random-variable.h"

#include "ns3/simulator.h"

#include "ns3/log.h"

#include "ns3/uinteger.h"

#include "ns3/double.h"

#include "ns3/wifi-mac.h"

#include "ns3/assert.h"

#include <vector>

NS_LOG_COMPONENT_DEFINE ("MinstrelWifiManager");

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (MinstrelWifiManager);

TypeId

MinstrelWifiManager::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::MinstrelWifiManager")

    .SetParent<WifiRemoteStationManager> ()

    .AddConstructor<MinstrelWifiManager> ()

    .AddAttribute ("UpdateStatistics",

                   "The interval between updating statistics table ",

                   TimeValue (Seconds (0.1)),

                   MakeTimeAccessor (&MinstrelWifiManager::m_updateStats),

                   MakeTimeChecker ())

    .AddAttribute ("LookAroundRate", 

                   "the percentage to try other rates",

                   DoubleValue (10),

                   MakeDoubleAccessor (&MinstrelWifiManager::m_lookAroundRate),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("EWMA", 

                   "EWMA level",

                   DoubleValue (75),

                   MakeDoubleAccessor (&MinstrelWifiManager::m_ewmaLevel),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("SegmentSize",

                   "The largest allowable segment size packet",

                   DoubleValue (6000),

                   MakeDoubleAccessor (&MinstrelWifiManager::m_segmentSize),

                   MakeDoubleChecker <double> ())

    .AddAttribute ("SampleColumn",

                   "The number of columns used for sampling",

                   DoubleValue (10),

                   MakeDoubleAccessor (&MinstrelWifiManager::m_sampleCol),

                   MakeDoubleChecker <double> ())

    .AddAttribute ("PacketLength",

                   "The packet length used for calculating mode TxTime",

                   DoubleValue (1200),

                   MakeDoubleAccessor (&MinstrelWifiManager::m_pktLen),

                   MakeDoubleChecker <double> ())

    ;

  return tid;

}

MinstrelWifiManager::MinstrelWifiManager ()

{}

MinstrelWifiManager::~MinstrelWifiManager ()

{}

void

MinstrelWifiManager::SetupPhy (Ptr<WifiPhy> phy)

{

  uint32_t nModes = phy->GetNModes ();

  for (uint32_t i = 0; i < nModes; i++)

    {

      WifiMode mode = phy->GetMode (i);

      AddCalcTxTime (mode, phy->CalculateTxDuration (m_pktLen, mode, WIFI_PREAMBLE_LONG));

    }

  WifiRemoteStationManager::SetupPhy (phy);

}

WifiRemoteStation *

MinstrelWifiManager::CreateStation (void)

{

  return new MinstrelWifiRemoteStation (this);

}

Time

MinstrelWifiManager::GetCalcTxTime (WifiMode mode) const

{

  for (TxTime::const_iterator i = m_calcTxTime.begin (); i != m_calcTxTime.end (); i++)

    {

      if (mode == i->second)

        {

          return i->first;

        }

    }

  NS_ASSERT (false);

  return Seconds (0);

}

void

MinstrelWifiManager::AddCalcTxTime (WifiMode mode, Time t)

{

  m_calcTxTime.push_back (std::make_pair (t, mode));

}

MinstrelWifiRemoteStation::MinstrelWifiRemoteStation (Ptr<MinstrelWifiManager> stations)

  :m_stations (stations),

  m_nextStatsUpdate (Simulator::Now () + stations->m_updateStats),

  m_col (0), 

  m_index (0), 

  m_maxTpRate (0), 

  m_maxTpRate2 (0), 

  m_maxProbRate (0),

  m_packetCount (0), 

  m_sampleCount (0), 

  m_isSampling (false), 

  m_sampleRate (0), 

  m_sampleRateSlower (false),

  m_currentRate (0),

  m_shortRetry (0),

  m_longRetry (0),

  m_retry (0),

  m_err (0),

  m_txrate (0),

  m_initialized (false)

{}

MinstrelWifiRemoteStation::~MinstrelWifiRemoteStation ()

{}

void 

MinstrelWifiRemoteStation::CheckInit(void)

{

  if (!m_initialized)

    {

      m_minstrelTable  =  MinstrelRate(GetNSupportedModes ());

      m_sampleTable = SampleRate(GetNSupportedModes (), std::vector<uint32_t> (m_stations->m_sampleCol));

      InitSampleTable ();

      RateInit ();

      m_initialized = true;

    }

}

void

MinstrelWifiRemoteStation::DoReportRxOk (double rxSnr, WifiMode txMode)

{

  NS_LOG_DEBUG("DoReportRxOk m_txrate=" << m_txrate);

}

void

MinstrelWifiRemoteStation::DoReportRtsFailed (void)

{

  NS_LOG_DEBUG("DoReportRtsFailed m_txrate=" << m_txrate);

  m_shortRetry++;

}

void

MinstrelWifiRemoteStation::DoReportRtsOk (double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

  NS_LOG_DEBUG ("self="<<this<<" rts ok");

}

void

MinstrelWifiRemoteStation::DoReportFinalRtsFailed (void)

{

  UpdateRetry ();

  m_err++;

}

void

MinstrelWifiRemoteStation::DoReportDataFailed (void)

{

  CheckInit();

  m_longRetry++;

  NS_LOG_DEBUG ("DoReportDataFailed " << this << "\t rate " << m_txrate << "\tlongRetry \t" << m_longRetry);

  /// for normal rate, we're not currently sampling random rates

  if (!m_isSampling)

    {

      /// use best throughput rate

      if( m_longRetry < m_minstrelTable[m_txrate].adjustedRetryCount)

        {

          ;  ///<  there's still a few retries left

        }

      /// use second best throughput rate

      else if (m_longRetry <= (m_minstrelTable[m_txrate].adjustedRetryCount +  

               m_minstrelTable[m_maxTpRate].adjustedRetryCount))

        {

          m_txrate = m_maxTpRate2;

        }

      /// use best probability rate

      else if (m_longRetry <= (m_minstrelTable[m_txrate].adjustedRetryCount +  

               m_minstrelTable[m_maxTpRate2].adjustedRetryCount + 

               m_minstrelTable[m_maxTpRate].adjustedRetryCount))

        {

          m_txrate = m_maxProbRate;

        }

      /// use lowest base rate	

      else if (m_longRetry > (m_minstrelTable[m_txrate].adjustedRetryCount +  

               m_minstrelTable[m_maxTpRate2].adjustedRetryCount + 

               m_minstrelTable[m_maxTpRate].adjustedRetryCount))

        {

          m_txrate = 0;

        }

    }

  /// for look-around rate, we're currently sampling random rates

  else

    {

      /// current sampling rate is slower than the current best rate

      if (m_sampleRateSlower)

        {

          /// use best throughput rate

          if (m_longRetry < m_minstrelTable[m_txrate].adjustedRetryCount)

            {

              ;	///<  there are a few retries left

            }

          ///	use random rate

          else if (m_longRetry <= (m_minstrelTable[m_txrate].adjustedRetryCount + 

                   m_minstrelTable[m_maxTpRate].adjustedRetryCount))

            {

              m_txrate = m_sampleRate;

            }

          /// use max probability rate

          else if (m_longRetry <= (m_minstrelTable[m_txrate].adjustedRetryCount +  

                   m_minstrelTable[m_sampleRate].adjustedRetryCount + 

                   m_minstrelTable[m_maxTpRate].adjustedRetryCount ))

            {

              m_txrate = m_maxProbRate;

            }

          /// use lowest base rate

          else if (m_longRetry > (m_minstrelTable[m_txrate].adjustedRetryCount +  

                   m_minstrelTable[m_sampleRate].adjustedRetryCount + 

                   m_minstrelTable[m_maxTpRate].adjustedRetryCount)) 

            {

              m_txrate = 0;

            }

        }

        /// current sampling rate is better than current best rate 

        else

          {

            /// use random rate

            if (m_longRetry < m_minstrelTable[m_txrate].adjustedRetryCount)

              {

                ;  ///< keep using it

              }

            /// use the best rate

            else if (m_longRetry <= m_minstrelTable[m_txrate].adjustedRetryCount + 

                     m_minstrelTable[m_sampleRate].adjustedRetryCount)

              {

                m_txrate = m_maxTpRate;

              }

            /// use the best probability rate

            else if (m_longRetry <= m_minstrelTable[m_txrate].adjustedRetryCount + 

                     m_minstrelTable[m_maxTpRate].adjustedRetryCount +  

                     m_minstrelTable[m_sampleRate].adjustedRetryCount)

              {

                m_txrate = m_maxProbRate;

              }

            /// use the lowest base rate

            else if (m_longRetry > m_minstrelTable[m_txrate].adjustedRetryCount + 

                     m_minstrelTable[m_maxTpRate].adjustedRetryCount +  

                     m_minstrelTable[m_sampleRate].adjustedRetryCount) 

              {

                m_txrate = 0;

              }

          }

    }

}

void

MinstrelWifiRemoteStation::DoReportDataOk (double ackSnr, WifiMode ackMode, double dataSnr)

{

  m_isSampling = false;

  m_sampleRateSlower=false;

  CheckInit ();

  m_minstrelTable[m_txrate].numRateSuccess++;

  m_minstrelTable[m_txrate].numRateAttempt++;

  UpdateRetry ();

  m_minstrelTable[m_txrate].numRateAttempt += m_retry;

  m_packetCount++;

  if (GetNSupportedModes () >= 1)

    {

      m_txrate = FindRate ();

    }

}

void

MinstrelWifiRemoteStation::DoReportFinalDataFailed (void)

{

  NS_LOG_DEBUG ("DoReportFinalDataFailed m_txrate=" << m_txrate);

  m_isSampling = false;

  m_sampleRateSlower=false;

  UpdateRetry ();

  m_minstrelTable[m_txrate].numRateAttempt += m_retry;

  m_err++;

  if (GetNSupportedModes () >= 1)

    {

      m_txrate = FindRate ();

    }

}

void

MinstrelWifiRemoteStation::UpdateRetry (void)

{

  m_retry = m_shortRetry + m_longRetry;

  m_shortRetry = 0;

  m_longRetry = 0;

}

Ptr<WifiRemoteStationManager>

MinstrelWifiRemoteStation::GetManager (void) const

{

  return m_stations;

}

WifiMode

MinstrelWifiRemoteStation::DoGetDataMode (uint32_t size)

{

  UpdateStats ();

  if (!m_initialized)

    {

      CheckInit ();

      /// start the rate at half way

      m_txrate = GetNSupportedModes () / 2;

    }

  return GetSupportedMode (m_txrate);

}

WifiMode

MinstrelWifiRemoteStation::DoGetRtsMode (void)

{

  NS_LOG_DEBUG ("DoGetRtsMode m_txrate=" << m_txrate);

  UpdateStats ();

  return GetSupportedMode (0);

}

uint32_t 

MinstrelWifiRemoteStation::GetNextSample ()

{

  uint32_t bitrate;

  bitrate = m_sampleTable[m_index][m_col];

  m_index++;

  /// bookeeping for m_index and m_col variables

  if (m_index > (GetNSupportedModes () -2)) 

    {

      m_index =0;

      m_col++;

      if (m_col >= m_stations->m_sampleCol)

        {

          m_col = 0;

        }

    }

  return bitrate;

}

uint32_t

MinstrelWifiRemoteStation::FindRate ()

{

  NS_LOG_DEBUG ("FindRate " << "packet=" << m_packetCount );

  if ((m_sampleCount + m_packetCount) == 0)

    {

      return 0;

    }

  uint32_t idx;

  /// for determining when to try a sample rate 

  UniformVariable coinFlip (0, 100);

  /**

   * if we are below the target of look around rate percentage, look around

   * note: do it randomly by flipping a coin instead sampling 

   * all at once until it reaches the look around rate

   */

  if ( (((100* m_sampleCount) / (m_sampleCount + m_packetCount )) < m_stations->m_lookAroundRate) &&

     ((int)coinFlip.GetValue ()) % 2 == 1 )

    {

      /// now go through the table and find an index rate

      idx = GetNextSample	();

      /**

       * This if condition is used to make sure that we don't need to use

       * the sample rate it is the same as our current rate

       */

      if (idx != m_maxTpRate && idx != m_txrate) 

        {

          /// start sample count

          m_sampleCount++;

          /// set flag that we are currently sampling

          m_isSampling = true;

          /// bookeeping for resetting stuff

          if (m_packetCount >= 10000) 

            {

              m_sampleCount = 0;

              m_packetCount = 0;

            }

          /// error check

          if (idx >= GetNSupportedModes	() || idx < 0 )

            {

              NS_LOG_DEBUG ("ALERT!!! ERROR");

            }

          /// set the rate that we're currently sampling

          m_sampleRate = idx;

          if (m_sampleRate == m_maxTpRate)

            {

              m_sampleRate = m_maxTpRate2;

            }

          /// is this rate slower than the current best rate

          m_sampleRateSlower = (m_minstrelTable[idx].perfectTxTime > m_minstrelTable[m_maxTpRate].perfectTxTime);

          /// using the best rate instead

          if (m_sampleRateSlower)

            {

              idx =  m_maxTpRate;

            }

        }

    } 

  ///	continue using the best rate

  else

    {

      idx = m_maxTpRate; 

    }

  NS_LOG_DEBUG ("FindRate " << "sample rate=" << idx);

  return idx;

}

void

MinstrelWifiRemoteStation::UpdateStats ()

{

  if (Simulator::Now () <  m_nextStatsUpdate)

    {

      return;

    }

  NS_LOG_DEBUG ("Updating stats="<<this);

  m_nextStatsUpdate = Simulator::Now () + m_stations->m_updateStats;

  Time txTime;

  uint32_t tempProb;

  for (uint32_t i =0; i < GetNSupportedModes (); i++)

    {        

      /// calculate the perfect tx time for this rate

      txTime = m_minstrelTable[i].perfectTxTime;       

      /// just for initialization

      if (txTime.GetMicroSeconds () == 0)

        {

          txTime = Seconds (1);

        }

      NS_LOG_DEBUG ("m_txrate=" << m_txrate << "\t attempt=" << m_minstrelTable[i].numRateAttempt << "\t success=" << m_minstrelTable[i].numRateSuccess);

      /// if we've attempted something

      if (m_minstrelTable[i].numRateAttempt)

        {

          /**

           * calculate the probability of success

           * assume probability scales from 0 to 18000

           */

          tempProb = (m_minstrelTable[i].numRateSuccess * 18000) / m_minstrelTable[i].numRateAttempt;

          /// bookeeping

          m_minstrelTable[i].successHist += m_minstrelTable[i].numRateSuccess;

          m_minstrelTable[i].attemptHist += m_minstrelTable[i].numRateAttempt;

          m_minstrelTable[i].prob = tempProb;

          /// ewma probability

          tempProb = ((tempProb * (100 - m_stations->m_ewmaLevel)) + (m_minstrelTable[i].ewmaProb * m_stations->m_ewmaLevel) )/100;

          m_minstrelTable[i].ewmaProb = tempProb;

          /// calculating throughput

          m_minstrelTable[i].throughput = tempProb * (1000000 / txTime.GetMicroSeconds());

        }

      /// bookeeping

      m_minstrelTable[i].prevNumRateAttempt= m_minstrelTable[i].numRateAttempt;

      m_minstrelTable[i].prevNumRateSuccess = m_minstrelTable[i].numRateSuccess;

      m_minstrelTable[i].numRateSuccess = 0;

      m_minstrelTable[i].numRateAttempt = 0;

      /// Sample less often below 10% and  above 95% of success

      if ((m_minstrelTable[i].ewmaProb > 17100) || (m_minstrelTable[i].ewmaProb < 1800)) 

        {

          /**

           * retry count denotes the number of retries permitted for each rate

           * # retry_count/2

           */

          m_minstrelTable[i].adjustedRetryCount = m_minstrelTable[i].retryCount >> 1;

          if (m_minstrelTable[i].adjustedRetryCount > 2)

            {

              m_minstrelTable[i].adjustedRetryCount = 2 ;

            }

        }

      else

        {

          m_minstrelTable[i].adjustedRetryCount = m_minstrelTable[i].retryCount;

        }

      /// if it's 0 allow one retry limit

      if (m_minstrelTable[i].adjustedRetryCount == 0)

        {

          m_minstrelTable[i].adjustedRetryCount = 1;

        }

    }

  uint32_t max_prob = 0, index_max_prob =0, max_tp =0, index_max_tp=0, index_max_tp2=0;

  /// go find max throughput, second maximum throughput, high probability succ

  for (uint32_t i =0; i < GetNSupportedModes (); i++) 

    {

      NS_LOG_DEBUG ("throughput" << m_minstrelTable[i].throughput << "\n ewma" << m_minstrelTable[i].ewmaProb);

      if (max_tp < m_minstrelTable[i].throughput) 

        {

          index_max_tp = i;

          max_tp = m_minstrelTable[i].throughput;

        }

      if (max_prob < m_minstrelTable[i].ewmaProb) 

        {

          index_max_prob = i;

          max_prob = m_minstrelTable[i].ewmaProb;

        }

    }

  max_tp = 0;

  /// find the second highest max

  for (uint32_t i =0; i < GetNSupportedModes (); i++) 

    {

      if ((i != index_max_tp) && (max_tp < m_minstrelTable[i].throughput))

        {

          index_max_tp2 = i;

          max_tp = m_minstrelTable[i].throughput;

        }

    }

  m_maxTpRate = index_max_tp;

  m_maxTpRate2 = index_max_tp2;

  m_maxProbRate = index_max_prob;

  m_currentRate = index_max_tp;

  if (index_max_tp > m_txrate)

    {

      m_txrate= index_max_tp;

    }

  NS_LOG_DEBUG ("max tp="<< index_max_tp << "\nmax tp2="<< index_max_tp2<< "\nmax prob="<< index_max_prob);

  /// reset it

  RateInit ();

}

void

MinstrelWifiRemoteStation::RateInit ()

{

  NS_LOG_DEBUG ("RateInit="<<this);

  for (uint32_t i = 0; i < GetNSupportedModes (); i++)

    {

      m_minstrelTable[i].numRateAttempt = 0;

      m_minstrelTable[i].numRateSuccess = 0;

      m_minstrelTable[i].prob = 0;

      m_minstrelTable[i].ewmaProb = 0;

      m_minstrelTable[i].prevNumRateAttempt = 0;

      m_minstrelTable[i].prevNumRateSuccess = 0;

      m_minstrelTable[i].successHist = 0;

      m_minstrelTable[i].attemptHist = 0;

      m_minstrelTable[i].throughput = 0;

      m_minstrelTable[i].perfectTxTime = m_stations->GetCalcTxTime (GetSupportedMode (i));

      m_minstrelTable[i].retryCount =1;

      m_minstrelTable[i].adjustedRetryCount =1;

    }

}

void

MinstrelWifiRemoteStation::InitSampleTable ()

{

  NS_LOG_DEBUG ("InitSampleTable="<<this);

  m_col = m_index = 0;

  /// for off-seting to make rates fall between 0 and numrates 

  uint32_t numSampleRates= GetNSupportedModes () - 1;

  uint32_t newIndex;

  for (uint32_t col = 0; col < m_stations->m_sampleCol; col++)

    {

      for (uint32_t i = 0; i < numSampleRates; i++ )

        {

          /**

           * The next two lines basically tries to generate a random number

           * between 0 and the number of available rates 

           */

          UniformVariable uv (0, numSampleRates);

          newIndex = (i + (uint32_t)uv.GetValue	()) % numSampleRates;	

          /// this loop is used for filling in other uninitilized places

          while	(m_sampleTable[newIndex][col] != 0)

            {

              newIndex = (newIndex + 1)%GetNSupportedModes ();

            }

          m_sampleTable[newIndex][col] = i+1;

        }

    }

}

void

MinstrelWifiRemoteStation::PrintSampleTable ()

{

  NS_LOG_DEBUG ("PrintSampleTable="<<this );

  uint32_t numSampleRates= GetNSupportedModes ();

  for (uint32_t i=0; i < numSampleRates; i++)

    {

      for (uint32_t j=0; j < m_stations->m_sampleCol; j++)

        {

          std::cout << m_sampleTable[i][j] << "\t";

        }

      std::cout << std::endl;

    }

}

void

MinstrelWifiRemoteStation::PrintTable ()

{

  NS_LOG_DEBUG ("PrintTable="<<this);

  for (uint32_t i=0; i < GetNSupportedModes (); i++)

    {

      std::cout << "index(" << i << ") = " << m_minstrelTable[i].perfectTxTime<< "\n";

    }

}

} //namespace ns3